Factors affecting the nature and effectiveness of subjective revision in sales forecasting: An empirical study

Recent empirical results have indicated that sales forecasts obtained from a quantitative model can be improved through subjective revision undertaken by management. This study seeks to determine the extent to which the improvement in forecast performance is dependent upon the individual revising the forecast rather than the specific product under consideration. As any improvement in the forecast is a direct consequence of the adjustment effected, differences in the nature of revision among the individuals concerned and between different types of product are also examined. The results reveal no statistically significant differences between the managers involved in revision activity in terms of their ability to improve the forecast; on the other hand, significant differences in the number of forecasts improved were found between different types of product. As far as the nature of subjective revision is concerned, the results show a significant variation both between different types of product and between managers. Further, the improvement in forecast performance obtained through revision was found to be positively related to the relative size of the adjustment applied.